Method for the manufacture of oxalates.



nA NoELo'r w 'annnnws, or DAVENPORT, IOWA METHOD non Tnn MANUFACTURE or'o'xALA'rns.

No Drawing.

To all whom, it may concern:

Be it known that I, LAUNCELOT W.'AN- Dimws, a citizen of the United States, re-

' siding at Davenport, in the county of Scott freely admitted.

and State of Iowa, have invented certain new and useful Improvements in Methods for the Manufacture of Oxalates, of which the following is a specification.

This in ention relates to an improved process or method for the manufacture of oxalat'es and oxalic acid.

In the usual method of producing oxalic acid forcommercial purposes, saw dust or other materialof like nature, is heated on pans with water and caustic alkali and the reaction completed by spreading the mixture on heated plates or pans to whlch the air is This method possesses many disadvantages and the object of the present invention is the provision of an improved method-which Wlll obviate the disadvantages of the old method and will result. in the production of a superior and addition the presence of a sufficient supply of the water demanded by the reaction is assured at all stages of the generating process by the introduction of such water in it in the form of superheated steam.

In carrying out the present-process a hol low drum is employed which is conveniently prcvic ed with a plurality of stirringarms on its interior, which may be conveniently extended from a revolving axle extending through the drum.- Into a drum of this char 'acter, is introduced saw dust or other material containing compounds belonging to the class of carbohydrates, and caustic soda, for xamplc. 500 lbs. of saw dust and 1000 lbs. of powdered caustic 'soda. The 'stirrer is actuated to thoroughly mix the charge which has been introduced into the drum and a current of steam superheated to 135 C, more or less, and under any low pressure, preferably atmospheric, is introduced into the drum. The charge will rap dly heat to the temperature of the steam Specification of ffietters Patent.

rammed June 24, 1913.

Application filed August 10, 1910. Serial No. 576.595.

which is introduced into the drum, owing.

in part to the condensation of the steam and its absorption by the solid caustic alkali.

The temperature of the steam as admitted to the drum is gradually raised until it is finally brought to 240 C. or even higher and this process is continued until an examination of a sample taken from the vessel shows that the reaction has been completed, which in most instances, will be in considerably less than eight hours from the starting of the process.

As, when the process is being carried out, the drum is completely filled with superheated steam, .it will be seen that air is excluded from the reaction mixture during the reactive period, so that all of the advantages of the vacuum processare obtained and the process may be at 'the same time much more economically practised. Furthermcre, by surrounding the mixture with an atmosphere of superheated steam, a more regular distribution of the high temperature required by the reaction is obtained.

, The crude product obtained as a result of the present process contains at least one-- third of its weight of oxalic acid and is of excellent color and furnishes liquors and calcium oxalate which are of a very pure character. From the product obtained by the above described process, oxalic acid may be' obtained by any of the processes known in the art.

I claim L'The method of heating the ,re-action mixture in the manufaclure of oxalic acid by the action of an alkali on-carbohydratcs consisting in placing it in an atmosphere of superheated steam at substantially atmospheric pressure.

2. The method of producing oxalates consisting in mixing caustic alkali with a material of the carbohydrateclass and placing the mixture in an atmosphere of superheated steam under low pressure.

3. The methodnf producing oxalates consisting in introducing a mixture of alkali and saw dust in a closed vessel, stirring the mixture and filling the vessel with superheated steamunder low pressure.

4. The method of producing oxalate-s consisting in introducing saw dust and allzali vessel, and simultaneously applying heat to 10 into a closed vessel, introducing superheated the exterior of the vessel. steam under low pressure into said vessel In testimony whereof I afiix my signature flfild continually and gradually increasing in presence of two Witnesses. t e temperature 0 'sai steam. w i

5. The method of producing oxalates con- LAUNLELOT ANDREWS sisting in introducing a mixture of alkali VVitnesses-z and sawdust in a vessel, introducing super- SOPHIA W. OLMs'rED, heated steam under low pressure into said JOHNC. OLMsrED. 

